ValueOf

ValueOf[T] provides the unique value of the type T where T is a type which has a single inhabitant. Eligible types are singleton types of the form stablePath.type, Unit and, if the -Yliteral-types compiler option has been specified, singleton types corresponding to value literals.

Instances of ValueOf[T] are provided implicitly for all eligible types. Typically an instance would be required where a runtime value corresponding to a type level computation is needed.

For example, we might define a type Residue[M <: Int] corresponding to the group of integers modulo M. We could then mandate that residues can be summed only when they are parameterized by the same modulus,

case class Residue[M <: Int](n: Int) extends AnyVal {
  def +(rhs: Residue[M])(implicit m: ValueOf[M]): Residue[M] =
    Residue((this.n + rhs.n) % valueOf[M])
}

val fiveModTen = Residue[10](5)
val nineModTen = Residue[10](9)

fiveModTen + nineModTen    // OK == Residue[10](4)

val fourModEleven = Residue[11](4)

fiveModTen + fourModEleven // compiler error: type mismatch;
                           //   found   : Residue[11]
                           //   required: Residue[10]

Notice that here the modulus is encoded in the type of the values and so does not incur any additional per-value storage cost. When a runtime value of the modulus is required in the implementation of + it is provided at the call site via the implicit argument m of type ValueOf[M].

Annotations: @implicitNotFound( msg = ... )
Source: ValueOf.scala

Linear Supertypes

AnyVal, Any

Instance Constructors

new ValueOf(value: T)

Value Members

final def !=(arg0: Any): Boolean

Test two objects for inequality.
Test two objects for inequality.
returns
true if !(this == that), false otherwise.

Definition Classes
Any
final def ##(): Int

Equivalent to x.hashCode except for boxed numeric types and null.
Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.
returns
a hash value consistent with ==

Definition Classes
Any
def +(other: String): String

Implicit information
This member is added by an implicit conversion from ValueOf[T] to any2stringadd[ValueOf[T]] performed by method any2stringadd in scala.Predef.
Definition Classes
any2stringadd
def ->[B](y: B): (ValueOf[T], B)

Implicit information
This member is added by an implicit conversion from ValueOf[T] to ArrowAssoc[ValueOf[T]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
@inline()
final def ==(arg0: Any): Boolean

Test two objects for equality.
Test two objects for equality. The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
returns
true if the receiver object is equivalent to the argument; false otherwise.

Definition Classes
Any
final def asInstanceOf[T0]: T0

Cast the receiver object to be of type T0.
Cast the receiver object to be of type T0.
Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expression List(1).asInstanceOf[List[String]] will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.
returns
the receiver object.

Definition Classes
Any
Exceptions thrown
ClassCastException if the receiver object is not an instance of the erasure of type T0.
def ensuring(cond: (ValueOf[T]) ⇒ Boolean, msg: ⇒ Any): ValueOf[T]

Implicit information
This member is added by an implicit conversion from ValueOf[T] to Ensuring[ValueOf[T]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: (ValueOf[T]) ⇒ Boolean): ValueOf[T]

Implicit information
This member is added by an implicit conversion from ValueOf[T] to Ensuring[ValueOf[T]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean, msg: ⇒ Any): ValueOf[T]

Implicit information
This member is added by an implicit conversion from ValueOf[T] to Ensuring[ValueOf[T]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean): ValueOf[T]

Implicit information
This member is added by an implicit conversion from ValueOf[T] to Ensuring[ValueOf[T]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def formatted(fmtstr: String): String

Returns string formatted according to given format string.
Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).

Implicit information
This member is added by an implicit conversion from ValueOf[T] to StringFormat[ValueOf[T]] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
@inline()
def getClass(): Class[_ <: AnyVal]

Returns the runtime class representation of the object.
Returns the runtime class representation of the object.
returns
a class object corresponding to the runtime type of the receiver.

Definition Classes
AnyVal → Any
final def isInstanceOf[T0]: Boolean

Test whether the dynamic type of the receiver object is T0.
Test whether the dynamic type of the receiver object is T0.
Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression 1.isInstanceOf[String] will return false, while the expression List(1).isInstanceOf[List[String]] will return true. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.
returns
true if the receiver object is an instance of erasure of type T0; false otherwise.

Definition Classes
Any
def toString(): String

Returns a string representation of the object.
Returns a string representation of the object.
The default representation is platform dependent.
returns
a string representation of the object.

Definition Classes
Any
val value: T
def →[B](y: B): (ValueOf[T], B)

Implicit information
This member is added by an implicit conversion from ValueOf[T] to ArrowAssoc[ValueOf[T]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc

Related Doc: package scala

final class ValueOf[T] extends AnyVal

Instance Constructors

new ValueOf(value: T)

Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

def +(other: String): String

def ->[B](y: B): (ValueOf[T], B)

final def ==(arg0: Any): Boolean

final def asInstanceOf[T0]: T0

def ensuring(cond: (ValueOf[T]) ⇒ Boolean, msg: ⇒ Any): ValueOf[T]

def ensuring(cond: (ValueOf[T]) ⇒ Boolean): ValueOf[T]

def ensuring(cond: Boolean, msg: ⇒ Any): ValueOf[T]

def ensuring(cond: Boolean): ValueOf[T]

def formatted(fmtstr: String): String

def getClass(): Class[_ <: AnyVal]

final def isInstanceOf[T0]: Boolean

def toString(): String

val value: T

def →[B](y: B): (ValueOf[T], B)

Inherited from AnyVal

Inherited from Any

Inherited by implicit conversion any2stringadd from ValueOf[T] to any2stringadd[ValueOf[T]]

Inherited by implicit conversion StringFormat from ValueOf[T] to StringFormat[ValueOf[T]]

Inherited by implicit conversion Ensuring from ValueOf[T] to Ensuring[ValueOf[T]]

Inherited by implicit conversion ArrowAssoc from ValueOf[T] to ArrowAssoc[ValueOf[T]]

Ungrouped